Great, high quality and fun game!
I love the gameplay mechanic, it's super engaging and has you on the edge of your seat, and the art, music and UI all mesh together really well :)
The controls were a little awkward with mouse, but that makes sense as this feels like a more mobile-oriented experience. I think that having some enemies that required you to use certain spells, or adding some kind of timing aspect where if you cast a certain spell at a certain time you can deal a huge amount of damage to the enemy would be fun ways to expand upon this mechanic and add more incentive to try out different spells.
Great job!! :D